The personal computer has enjoyed more and more frequent and versatile application in commercial and private areas in communications technology, particularly in telecommunications. A comfortable user surface enables an uncomplicated operation and utilization of the personal computer. In telecommunications, the personal computer can be coupled, for example, to a subscriber terminal equipment (telephone, switching system). The services (for example telephone number register, computer-assisted dialing, telephone manager) that are possible in telecommunications technology can be designed more transparent and user-friendly for the telecommunication subscriber on the basis of this combination. The combination of personal computer/subscriber terminal equipment makes it possible for the telecommunication subscriber to select the call numbers of another telecommunication subscriber stored in the personal computer from a telephone number register and to initiate a call set-up with the personal computer. It is of particular help in the selection of a telecommunication subscriber when telephone numbers from an electronic telephone book can be selected at the personal computer and connections can be set up to other telecommunication subscribers.
The invention is directed to a circuit arrangement for data conversion in a data transmission between a serial data interface of a personal computer and a serial data interface of a communication equipment.
Given a combination of a personal computer with a subscriber terminal equipment such as, for example, a switching system or an added-feature telephone having a plurality of function keys, additional transmission paths are required within the device combination. Communication is required due to the collaboration of the personal computer with the communication equipment. This requires a continuous occupation of a V.24 data interface at the personal computer.
Up to now, it was standard to employ a specific modem (Hayes modem) given a telephone number selection implemented with the personal computer. These modems are thereby installed, for example, at an interchange point between a public communication network and private lines. A further possibility of arranging a Hayes modem in system-oriented fashion given the combination of personal computer and subscriber terminal equipment is that the Hayes modem is integrated on a PC card and is inserted in the personal computer at a free card slot. A specific PC card, for example a plug-in modem having a connected telephone, assumes the function of the Hayes modem. The occupation of a PC card slot and/or the occupation of at least one defined data interface considerably limits the possible use of the personal computer. In favor, for example, of a telecommunications-oriented use of the personal computer, the integration of circuits for system expansion that are implementable on pluggable PC cards must thus be foregone.